A conventional vehicular lighting fixture includes a lamp body having an inner surface which is subjected to a surface treatment (e.g. a reflective coating) and a lens which is welded to the lamp body. FIG. 5 shows one such vehicular lighting fixture identified by reference letter a.
Referring to FIG. 5, the lamp body b is made of a thermoplastic resin, and a welding leg c protruding in the forward direction is formed on a peripheral portion of an opening defined by the lamp body b. The lens d is also made of a thermoplastic resin, and likewise has a welding leg e formed on a peripheral portion of the lens which protrudes in the rearward direction. The welding leg e has the same width as the welding leg c formed on the lamp body b.
During assembly, the welding leg c formed on the lamp body b and the welding leg e formed on the lens d are welded to each other. However, prior to this assembly, the inner face of the lamp body b is subjected to a surface treatment to apply a coating, plating or the like, as identified by reference letter f.
The aforementioned vehicular lighting fixture a is disadvantageous in that a welding face of the welding leg c formed on the lamp body b is also subjected to the surface treatment f. The presence of the surface treatment on the welding face leads to a decrease in bonding strength between the welding leg c formed on the lamp body b and the welding leg e formed on the lens d.
Furthermore, when the welding faces of the welding legs c and e formed on the lamp body b and the lens d, respectively, are brought into contact with each other, they may be offset from each other in the lateral direction. In such a case, the welding area is reduced, which results in a further decrease in bonding strength between the welding legs c and e.
It is thus an object of the present invention to prevent a decrease in bonding strength between a lamp body and a lens of a vehicular lighting fixture, where the lamp body and the lens are welded to each other and the inner face of the lamp body is subjected to a surface treatment.